This invention relates to a reference voltage-generating circuit, and more particularly to a reference voltage-generating circuit of simple arrangement which can produce a low reference voltage.
Recently in the field of a semiconductor device, prominent development is advancing with respect to an integrated circuit, large scale integrated (LSI) circuit and very large scale integrated (VLSI) circuit all constructed by forming a large number of semiconductor elements in a single chip. With these integrated circuits, each semiconductor element has to be biased by a prescribed level of reference voltage. To date, therefore, various reference voltage-generating circuits have been proposed. For example, a discussion (by R. J. Widlar) entitled "New Developments in IC Voltage Regulators" given in IEEE journal of solid-state circuits, Vol SC-6, No. 1, February 1971 discloses a circuit for generating a reference voltage corresponding to the extrapolated energy band-gap voltage of a semiconductor element. Since the conventional reference voltage-generating circuit produces a reference voltage having a higher level than 1 volt, the drive power source of this circuit should actually have a higher level of voltage than 1 volt. If, in case the conventional reference voltage-generating circuit is applied to an integrated circuit used with an apparatus such as a watch or camera which is operated by a power source of relatively low voltage, the power source voltage drops, than the reference voltage-generating circuit will be disabled. Therefore, the higher the level of reference voltage which the reference voltage circuit should produce, the narrower the range in which the reference voltage circuit can be operated, because of the necessity of providing drive power source having a higher level of voltage. With an integrated circuit biased by high voltage, each semiconductor element is generally demanded to have a higher withstand voltage, and consequently increases in size, resulting in a decline in the degree of integration. Further if biased by higher voltage, an integrated circuit will consume a larger amount of power, and rise in temperature due to Joule heat. This undesirable event deteriorates the property of the respective semiconductor elements, leading to a decline in the reliability of an integrated circuit.